Restless sleep, interrupted or with little sleep, is a problem many people face, especially on warm nights. But what temperature is considered too warm?
A new study with a group of 50 volunteers over the age of 60 living in Boston, USA, found that the ideal temperature range for the most restorative sleep in older adults is between 20 and 25°C (68 to 77°F).
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When temperatures rose from 25°C to 30°C, the sleep efficiency of the study’s participants – the amount of time they spend sleeping after getting into bed for some shut-eye – decreased by up to 10%.
With nights getting warmer as the planet heats up, the study’s findings support measures to improve the thermal comfort of homes, especially elderly homes and public housing. Other research is finding solutions beyond air conditioning, such as reflective paints and other construction materials.
Historical data and longitudinal studies also show that past temperature increases likely affected sleep patterns significantly, with further warming set to disrupt more sleepers.
By 2099, warmer temperatures might erode about 50 hours of sleep per person, per year. The elderly are among the most vulnerable to thermal stress, day or night.
Many sleep studies have been conducted in laboratory settings with controlled temperature, while this new study tracked the sleep patterns and temperatures of people within their own homes.
Participants, aged 65 or older, had indoor temperature and humidity sensors installed in their rooms and wore a ring-like device at night to track their sleep, skin temperature, heart rate, and movement.
In total, the researchers collected nearly 11,000 person-nights of sleep and environmental data for analysis.
Although temperatures between 20 and 25°C promote the most restorative sleep, the study found a “big difference among individuals, meaning each person has their own ideal temperature range for sleep, which might even change over time,” says Baniassadi.
The study was published in the Science of The Total Environment.
